In drive hubs of muscle-driven vehicles with two wheels with a foot pedal drive and roller chain transmissions, like conventional bicycles for instance, the tensile force is transferred into the tightened strand of the drive chain on a small sprocket wheel on the driver of the back wheel hub. There a torsional moment is created which is transferred over at least one torque path to the sleeve of the back wheel hub.
The hubs can have a gear inside the hub, which can be switched mechanically from outside with a switching device and a switch, or with the help of electrical components, or automatically depending on the hub rotational speed or on the torsional moment in the torque path through the hub.
Usually, the drive hubs have a freewheel, which interrupts the torque path through the hub to the hub shell if the hub shell is rotated further, but from the driver side no rotational movement occurs.
The relations in the torque path through the hub change if a rotational movement is initiated to the hub shell instead of to the driver. The backwards rotational direction with an opposite rotation to the hub shell then corresponds to the reverse direction of the freewheel in the torque path. The torque path is not interrupted in this case. The directionality of the rotation is opposite to the directionality with a forwards rotation, but the torsional moments present in the torque path correspond to those of a forward rotation. The rotational movement is transferred to the driver and from there over the drive chain to the foot pedal drive. In other words, when the bicycle is moved backwards, causing the wheel and hub shell to rotate backwards, the cranks and pedals also move in reverse. This movement can be harmful and undesirable.
A backwards movement of the foot pedals is harmful when, for instance, a bicycle is parked in a bicycle storage facility. The foot pedal is then in the wrong position under certain circumstances, for instance if the bicycle is placed right next to another bicycle in the storage facility to save space. If a bicycle is fitted with a kickstand near the bottom bracket shell, when the bicycle is parked with the retracted kickstand, the foot pedal can hit against the stand and cause problems.
The moving pedals can also hit the leg of the bicyclist in a harmful way, when he pushes the bicycle in front of himself.
The moving pedals are especially harmful if a folding bicycle which is folded up, is pushed backwards, and the pedals, which were first positioned in free, areas between parts of the bicycle frame, hit these parts of the bicycle frame when the bicycle is moved forward and further movement is prevented. In addition, there is then the danger of damage to the bicycle frame.